Faculty Publications

Title

Molecular simulations of intermediate and long alkanes adsorbed on graphite: Tuning of non-bond interactions

Document Type

Article

Keywords

Alkanes on graphite, Long molecules on graphite, Molecular dynamics, Scaling of CHARMM parameters, Surface phase transitions

Journal/Book/Conference Title

Journal of Molecular Modeling

Volume

17

Issue

4

First Page

811

Last Page

816

Abstract

The interplay between the torsional potential energy and the scaling of the 1-4 van der Waals and Coulomb interactions determines the stiffness of flexible molecules. In this paper we demonstrate for the first time that the precise value of the nonbond scaling factor (SF)-often a value assumed without justification-has a significant effect on the critical properties and mechanisms of systems undergoing a phase transition, and that, for accurate simulations, this scaling factor is highly dependent on the system under consideration. In particular, by analyzing the melting of n-alkanes (hexane C6, dodecane C12, tetracosane C24) on graphite, we show that the SF is not constant over varying alkane chain lengths when the structural correlated transformations are concerned. Instead, monotonic decrease of SF with the molecular length drives a cross-over between two distinct mechanisms for melting in such systems. In a broad sense we show that the choice for SF in any simulation containing adsorbed or correlated long molecules needs to be carefully considered. © 2010 Springer-Verlag.

Original Publication Date

4-1-2011

DOI of published version

10.1007/s00894-010-0770-0

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